// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)

package org.xbill.DNS;

import java.io.Serializable;
import java.util.*;

/**
 * A set of Records with the same name, type, and class. Also included are all
 * RRSIG records signing the data records.
 * 
 * @see Record
 * @see RRSIGRecord
 * 
 * @author Brian Wellington
 */

public class RRset implements Serializable {

	private static final long serialVersionUID = -3270249290171239695L;

	/*
	 * rrs contains both normal and RRSIG records, with the RRSIG records at the
	 * end.
	 */
	private List rrs;
	private short nsigs;
	private short position;

	/** Creates an empty RRset */
	public RRset() {
		rrs = new ArrayList(1);
		nsigs = 0;
		position = 0;
	}

	/** Creates an RRset and sets its contents to the specified record */
	public RRset(Record record) {
		this();
		safeAddRR(record);
	}

	/** Creates an RRset with the contents of an existing RRset */
	public RRset(RRset rrset) {
		synchronized (rrset) {
			rrs = (List) ((ArrayList) rrset.rrs).clone();
			nsigs = rrset.nsigs;
			position = rrset.position;
		}
	}

	private void safeAddRR(Record r) {
		if (!(r instanceof RRSIGRecord)) {
			if (nsigs == 0)
				rrs.add(r);
			else
				rrs.add(rrs.size() - nsigs, r);
		} else {
			rrs.add(r);
			nsigs++;
		}
	}

	/** Adds a Record to an RRset */
	public synchronized void addRR(Record r) {
		if (rrs.size() == 0) {
			safeAddRR(r);
			return;
		}
		Record first = first();
		if (!r.sameRRset(first))
			throw new IllegalArgumentException("record does not match "
					+ "rrset");

		if (r.getTTL() != first.getTTL()) {
			if (r.getTTL() > first.getTTL()) {
				r = r.cloneRecord();
				r.setTTL(first.getTTL());
			} else {
				for (int i = 0; i < rrs.size(); i++) {
					Record tmp = (Record) rrs.get(i);
					tmp = tmp.cloneRecord();
					tmp.setTTL(r.getTTL());
					rrs.set(i, tmp);
				}
			}
		}

		if (!rrs.contains(r))
			safeAddRR(r);
	}

	/** Deletes a Record from an RRset */
	public synchronized void deleteRR(Record r) {
		if (rrs.remove(r) && (r instanceof RRSIGRecord))
			nsigs--;
	}

	/** Deletes all Records from an RRset */
	public synchronized void clear() {
		rrs.clear();
		position = 0;
		nsigs = 0;
	}

	private synchronized Iterator iterator(boolean data, boolean cycle) {
		int size, start, total;

		total = rrs.size();

		if (data)
			size = total - nsigs;
		else
			size = nsigs;
		if (size == 0)
			return Collections.EMPTY_LIST.iterator();

		if (data) {
			if (!cycle)
				start = 0;
			else {
				if (position >= size)
					position = 0;
				start = position++;
			}
		} else {
			start = total - nsigs;
		}

		List list = new ArrayList(size);
		if (data) {
			list.addAll(rrs.subList(start, size));
			if (start != 0)
				list.addAll(rrs.subList(0, start));
		} else {
			list.addAll(rrs.subList(start, total));
		}

		return list.iterator();
	}

	/**
	 * Returns an Iterator listing all (data) records.
	 * 
	 * @param cycle
	 *            If true, cycle through the records so that each Iterator will
	 *            start with a different record.
	 */
	public synchronized Iterator rrs(boolean cycle) {
		return iterator(true, cycle);
	}

	/**
	 * Returns an Iterator listing all (data) records. This cycles through the
	 * records, so each Iterator will start with a different record.
	 */
	public synchronized Iterator rrs() {
		return iterator(true, true);
	}

	/** Returns an Iterator listing all signature records */
	public synchronized Iterator sigs() {
		return iterator(false, false);
	}

	/** Returns the number of (data) records */
	public synchronized int size() {
		return rrs.size() - nsigs;
	}

	/**
	 * Returns the name of the records
	 * 
	 * @see Name
	 */
	public Name getName() {
		return first().getName();
	}

	/**
	 * Returns the type of the records
	 * 
	 * @see Type
	 */
	public int getType() {
		return first().getRRsetType();
	}

	/**
	 * Returns the class of the records
	 * 
	 * @see DClass
	 */
	public int getDClass() {
		return first().getDClass();
	}

	/** Returns the ttl of the records */
	public synchronized long getTTL() {
		return first().getTTL();
	}

	/**
	 * Returns the first record
	 * 
	 * @throws IllegalStateException
	 *             if the rrset is empty
	 */
	public synchronized Record first() {
		if (rrs.size() == 0)
			throw new IllegalStateException("rrset is empty");
		return (Record) rrs.get(0);
	}

	private String iteratorToString(Iterator it) {
		StringBuffer sb = new StringBuffer();
		while (it.hasNext()) {
			Record rr = (Record) it.next();
			sb.append("[");
			sb.append(rr.rdataToString());
			sb.append("]");
			if (it.hasNext())
				sb.append(" ");
		}
		return sb.toString();
	}

	/** Converts the RRset to a String */
	public String toString() {
		if (rrs == null)
			return ("{empty}");
		StringBuffer sb = new StringBuffer();
		sb.append("{ ");
		sb.append(getName() + " ");
		sb.append(getTTL() + " ");
		sb.append(DClass.string(getDClass()) + " ");
		sb.append(Type.string(getType()) + " ");
		sb.append(iteratorToString(iterator(true, false)));
		if (nsigs > 0) {
			sb.append(" sigs: ");
			sb.append(iteratorToString(iterator(false, false)));
		}
		sb.append(" }");
		return sb.toString();
	}

}
